1. Field of the Invention
The present invention relates to the field of block co-polymers and nano-lithography.
2. Related Art
Developments in colloidal particle synthesis enable one to engineer nanoparticles with controlled size, shape, and chemical composition. Numerous studies have demonstrated the significant impact of nanoparticle-based materials in life sciences, microelectronics, light manipulation, energy harvesting and storage. Co-assemblies of nanoparticles and organic building blocks clearly hold promise for generating nanocomposites using different elements on the periodic table that combine the advantages of both families of building blocks. To fulfill these promises, at least two requirements must be satisfied. One is to control the spatial arrangement of nanoparticles spanning multiple length scales in a reproducible manner, so as to modulate inter-particle coupling and the collective properties of nanocomposites. The other is to understand and manipulate the kinetics of the assembly process to ensure compatibility with existing fabrication infrastructures. To be relevant, the fabrication process must be rapid, completed within a few minutes to minimize degradation of nanoparticle properties due to exposure to the processing environment and for compatibility with nanomanufacturing.
In comparison to many current approaches such as DNA and controlled solvent evaporation, block copolymers (BCPs) provide scalable platforms to obtain nanoscopic organization of nanoparticles, but require favorable nanoparticle-polymer interactions to achieve nanoparticle dispersion, and it remains difficult to control inter-particle ordering within BCP microdomains. Additionally, their self-assembly processes typically require tens of minutes or hours to complete and can lead to degradation of inherent optoelectronic properties of the nanoparticles. Thermal annealing alone or in conjunction with solvent annealing has been used to accelerate the assembly process, but is not suitable for temperature sensitive nanoparticles.
BCP-based supramolecules are constructed by non-covalently attaching small molecules to polymer side chains. The presence of small molecules eliminates the need to modify either the nanoparticle ligand or polymer for nanoparticle incorporation and improve inter-particle ordering within BCP microdomains. 1-, 2- and 3-D nanoparticle arrays can be obtained in thin films of supramolecular nanocomposites via solvent annealing for a range of nanoparticles or nanoparticle mixtures. Kinetically, the presence of small molecules also provides unique opportunities to manipulate the energy landscape of the assembly process and to accelerate the assembly kinetics so that inherent properties of nanoparticles can be maintained and continuous thin film processing techniques can be implemented for device fabrication. However, the supramolecular nanocomposite has at least 5 components during solvent annealing, making it extremely challenging to manipulate the assembly process.